Code Generation for Constant Multiplication/Division

By Nikolai Golovchenko. See https://www.golovchenko.org/home/constdivmul for a working online form and source code.

See:

Expression Evaluator

See also:

Questions:

danmiller0 at yahoo.com asks:
IS there a way of getting this code generation program in a simple windows program? It would be handy for when I am working from a workstation that does not have internet access.

The program does have a command line mode (not GUI) so it could be used locally... If there is enough interest, I could sell offline versions. Perhaps this would help to support the site? +

Comments:

jd at xtremepowersystems.net " I would definitely buy a version that supported the PIC18 parts, so that the MULWF instruction was used whenever possible!
" +
ebp1 at telus.net
When used for division, except in cases where the sum of the terms exactly equals the divisor (e.g. divisor is 8/3 = 2.6666667), the computed quotient will always be slightly smaller than the actual quotient. Rounding can be helpful, particularly with small quotients. Before the final shift, simply examine the highest-order bit that would be shifted out and add it after the final shift.
e.g. if the last shifting is 4 places and the bits that would be shifted out are 1xxx, add 1 after the last shift.
Try this for 9 divided by 3, using 7 terms. Without rounding, the quotient will be 2. Rounding "fixes" that.
+
pic at harry-arends.nl " When i use the code to make a routine that does arg*10 is works wel but when i want to make a divider using 1/10 is produces some useless code." James Newton replies: Please do not enter "1/10". Instead enter the RESULT of 1/10 which is ".1". Given .1, it generates very nice code for dividing by 10.+
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Interested:

file: /Techref/piclist/codegen/constdivmul.htm, 5KB, , updated: 2022/2/16 11:24, local time: 2024/11/22 17:15,

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Input/Output register name:	Input register size, bits	Bytes order : big endian little endian	This application is mirrored at: - https://www.golovchenko.org/home/constdivmul
Multiply by constant: Tip: To divide by a number, enter the value of 1/number into the field.		Maximum error in constant approximation, % Round result
Temporary register name:		Select processor: PIC SX Help